According to the relationship between acceleration and moving distance,

For armor1/2at2 = 60u1= at = 60 * 2/t =10m/s.

For b1/2at2 = 55u1= at = 55 * 2/t = 55/6m/s.

For b1/2at2 = 50u1= at = 50 * 2/t = 50/6m/s.

After 30 seconds.

A runs again 10*30=300m, and the position is 60+300 = 360 m.

B ran 55/6*30=275m again, and the position was 55+275 = 330 m.

C ran 50/6*30=250m again, and the position was 50+250=300m.

Hope to adopt